Mark B's Build Thread

[Mark B.]

I tackled my most ambitious carbon fiber project so far -- made air ducts for the radiator (both in and out). I'll post a video going through the process, but in the mean-time here are the basics and some pics.

I made plugs by layering up foam boards to get the overall shape, sanded them to clean up the shape and round the corners, then used spackle and primer for a final clean-up. After that packing tape to help with the mold release then a few coats of mold-release wax.

Here's the inlet plug ready to lay up:

I followed the same process for the exit / hood vent but that shape was much more complicated of course. I wet-laid the carbon/epoxy with 4 layers at 45* angles for strength. My epoxy has a pot life of about 30 mins with our high humidity so I had to do 2 batches for the inlet duct and 4 batches for the exit duct just because of the size and how long it was taking me to get the carbon fully wetted and remove excess epoxy.

After a 24 hour cure, I de-molded them. The inlet came out no problem since it's 3-sided. The exit duct not so much since it's 4-sided and a pretty complex shape. Unfortunately I had to destroy my plug to get it out. I need to find someone with a 3D scanner to make a file just in case it ever gets damaged, and I have to re-make it (the mold process took forever; I don't ever want to do that again).

Here are some shots of them both complete. The inlet screws in to my front clam brackets. The outlet bolts to a bracket on the floorpan just behind the radiator with the top bolted to my radiator shroud, and the back rests on a carbon tube that replaced the factory steel cross-bar. So far they work great. I wasn't having any overheating problems before, but was getting a lot of heat coming up the sides of the window/doors with my crude ABS heat deflector. Now there's absolutely none. I have my next track day at COTA on May 11 so that will be the real test.

 

[Joel K]

Awesome work Mark, beautifully integrated into the front clam.

 

[Mark B.]

Awesome work Mark, beautifully integrated into the front clam.

Thanks Joel!

 

[Howard Jones]

Ya, you could sell those as a set. Two options. Fiberglass or CF.

 

[Mark B.]

I've never been thrilled with the performance of the Vintage Air system in the SLC. In Texas heat it couldn't keep up on 100+ summer days particularly with the canopy acting like a greenhouse in the sun (even with tinted side windows). I have the factory vent locations and also opened up the top of the monocoque like most builders do. I always noticed that even with the blower cranked up it just made more noise, but didn't increase flow that much. I didn't build my car to be comfortable, but I also don't want to be sweating like mad cruising around in the afternoon .

I decided to try drilling some more vent holes in the front of the evaporator plenum. I drilled 4 x 1.25" holes, so they're aimed right at the passenger's stomach. Then I bonded 45* PVC bends on two of them to aim them at the driver.

The difference is HUGE! Surprisingly, it didn't take much flow, if any, from the main vents at all since the fan flows a lot more than those vents can handle anyway. It now keeps the whole cabin nice and cool (that's 100* ambient in direct sunlight for 1.5 hours in my test drive). Also, I can crank the fan all the way if I want and you can really feel the difference. Side benefit is the fan is much quieter at all levels.

Because of the location under the dash, you can't see any of this while seated in driver or passenger seats.

(the box on front of the plenum is the controller for my electric water pump)

 

[Ken Roberts]

Cooler and quieter......that's a win win. Thanks for sharing this tip Mark.

 

[Jeff W]

This is the Vintage Air setup?

 

[Mark B.]

This is the Vintage Air setup?

Yes. Mine was delivered 2014 so not sure if they're using the same system still.

 

[Jeff W]

I haven’t picked a vendor yet. Like you said, complaints about the interior heat are common, so I wrote VA and Restomod to see if I could get BTU/CFM info, but neither of them had anything to share. Now that you’ve pointed out that modding the outlets gets better AC effect I might go with VA’s unit.

 

[Mark B.]

A local kid asked to do a photo shoot to practice / build up his portfolio. He did a pretty good job! Here are a few of my favorites:

 

[Mark B.]

At a cruise in a few weeks back a random guy comes up and asks me if I'd do a video shoot with him. We ended up doing it a week ago and turns out he and his brother have a full professional setup. I was surprised how well it turned out!

 

[Randy V]

Great video!
Careful with those burnouts now!!!

 

[Hector]

Great video Mark!!! I saw it on facebook before

 

[Mark B.]

When you get bored on your phone with AI. "Make this car look like it's in a SpeedRacer cartoon"

This one was kind of cool -- some kid took pics of the car in a grocery store parking lot and messaged me on Instagram a week later. Made it look like the car was a model he built. Very creative kid!

 

[Mark B.]

I had my 2nd track day at COTA this past Sunday. Had a great time and the car didn't have any major issues (i.e. nothing broke and I didn't crash). I'm slowly getting my times down, but 2:40 is still crap (down from 2:48). I'm being VERY conservative/patient though -- not like I'm competing for anything.

A few of the big things I noticed this time:

1. Brake pad knock-back is BAD. The C4 hubs aren't shot, but on the long straights I had to pump the pedal pretty deep one time before it tightened up. That caused me to be extra conservative on the brakes (a second or two coasting time while pumping it up). I have all the parts to swap in C7 hubs which should fix the knock-back, so will definitely do that before I go back to the track. Aside from that the stock Brembos with Carbotech XP12 track pads worked great. I also have the parts for an MK60E5 ABS, but that's lower on the priority list since I'm not pushing it hard enough yet.
2. Throttle is WAY too sensitive the way I currently have it set up. I had lowered the throttle pedal after my 1st track day to make heel/toe align better, but in the process cut the travel by almost half. It's only slightly annoying on the street, but mid-corner on the track (coupled with the fact that my engine is a bit high-strung) means any pedal movement spins the car. I found this out by spinning the car 3 separate times. Fortunately, COTA is a great track with lots of runoff, so no harm done. I let my instructor drive it for a few laps as well (I rode with him in his car first so I was comfortable he wasn't insane). He spun out once as well for the same reason. He commented that he was impressed that I was driving as smoothly as I was between the pad knock-back and throttle. I'll definitely be adjusting the throttle linkage before heading back to the track.
3. Chassis balance was great. Aside from the first two issues, corner entry, mid, and exit was great. As long as I didn't move the throttle, the car stayed super stable at any speed. Aside from spinning it once, my instructor loved it. For me, though, it's a little like giving a toddler a machine gun.
4. Temps were fine. No issues with coolant (maxed out at 220 on a 93-degree day), oil maxed out at 240 (I have an oil cooler with a duct in the side vent, but no fan). No other issues with the car. In fact, I was too lazy to use my trailer, so I drove it to/from the track.

So I'll call it a win since I had fun, didn't break anything, and found a couple more things to tweak on the car and have even more fun next time.

 

[Hector]

Thanks for the detailed update, Mark. Sounds like a lot of fun, I may go there with you next year once I move to New Braunfels and you and Howard can help me take baby steps at COTA. Getting to know the limits on the track is super important , I have had the tail break loose a few times, luckily I was not going crazy and could control it easily , but your analogy is spot on, I do feel like a toddler with a machine gun.

 

[Mark B.]

Knocked out a couple projects this month after my last track day.
1) I completed the upgrade to C7 wheel bearings all around, including ARP studs. Basically followed what a few guys did in this thread. I opted for C7 bearings since I'm going to be adding a BMW MK60E5 later and it can work with the C7 bearing's active magnetic wheels. I picked up one of the last sets of Jim Dulaney's front adapters which made that end pretty easy. For the rears, I found a local machine shop to elongate the holes and bought new stub axles that Ken had for sale. I ground/drilled out both front and rears to accommodate BMW wheel speed sensors so I can install the ABS down the road (yes they will work with C7 bearing active wheels). Lastly, the new stub axles require a 1" longer axle shaft on both sides, so picked those up from the Driveshaft Shop and swapped my CV's over.

2) I've been wanting to swap / upgrade my wheels for a while now and Apex Wheels' Black Friday sale finally got me off the fence. I went with VS-5RS (lightweight forged) 18X10-ET32 front, 19X12.5-ET55 rear. They sell offsets to fit a C6 widebody. They sit a little farther out than my old Forgestars (which were stock C6 Z06 sizes: 18X9.5-ET40 front 19X12-ET59 rear), but still plenty of clearance front and rear. I kept my existing tires which are stock C6 Z06 sizes. They look great IMHO and best of all, save exactly 2 lbs each in front and 5 lbs each rear for a total of 14 lbs reduction!

The front adaptors were easy to install with a little bit of clearancing on the uprights. They have mounting ears for brake ducts so was able to reuse my ducts with a little trimming.

Machined rear upright

New wheels!

 

[Mark B.]

Well I had a lifter go bad so the motor is out. So while the car is apart, I'll see what other projects I can get done, like fixing a tiny pinhole in the radiator, pedal box adjustments/mechanical brake light switch, blah, blah, blah.

To save garage space, this is what my home office will look like for a couple months

 

[Mark B.]

Experimenting with center cap logo. This is literally just a waterproof vinyl sticker on top of a blank center cap. What do you guys think?

 

[Joel K]

Experimenting with center cap logo. This is literally just a waterproof vinyl sticker on top of a blank center cap. What do you guys think?
View attachment 152160

Looks good Mark, how durable do you think it would be?